KW45B41Z83AFPA Custom Board – Multicore (RPMsg) Initialization Failure in wireless_uart Example

[kiranshingote]

Hello Team,

I have designed a custom board based on the KW45B41Z83AFPA (6 × 6 mm package). On this custom board, I have successfully verified UART, GPIO, and CAN, which are all working as expected. However, I am unable to get the wireless_uart SDK example to work.

Steps followed

1. Imported the kw45b41zevk_wireless_uart_bm SDK example into MCUXpresso.
2. Modified the device part number from KW45B41Z83AFTA to KW45B41Z83AFPA in the .cproject file.
3. Updated pin configuration using ConfigTools.
4. Allowed MCUXpresso to automatically regenerate the code.
5. Removed all the errors.
6. Debugged the application using MCUXpresso IDE LinkServer probe.

Issue observed

The application gets stuck in the PLATFORM_InitMulticore() function.
The call to HAL_RpmsgMcmgrInit() returns a non-zero value, causing the assertion to trigger.

Because of this, the NBU–CM33 multicore initialization does not complete.

I followed the same migration procedure for UART, GPIO, and CAN SDK examples, and those applications run correctly on the custom board.

Additional information

• I have generated a custom NBU image using the MCUXpresso Secure Provisioning Tool.
• I successfully downloaded the NBU firmware once.
• The AN14003 application note was followed to create the .sb file.

Despite this, the wireless example still fails with the same multicore/RPMsg initialization issue.

Questions

1. Is the procedure I followed to migrate the SDK example for a different package correct?
2. Why does multicore (RPMsg/NBU) initialization fail even after programming the NBU?
3. Does a new KW45 MCU come with a pre-programmed NBU firmware, or is it blank by default?
4. Is it possible to reprogram or overwrite the NBU firmware on the KW45 device?

I would appreciate your guidance on how to correctly bring up the wireless functionality on a custom KW45 board.

Thank you for your support.

[sofiaurueta]

Hello, hope you are doing well.

In a KW45 factory chip, the keys in the fuses are null. For custom boards, you need to write your keys and generate the image for the NBU based on your keys.

For the KW45B41Z-EVK board, NXP provides the default keys in fuse. However, for the KW45 chip received from the factory, by default, the SBKDK and RoTKTH keys in the fuse are null. Therefore, writing these two keys to fuse is essential. Otherwise, the sb3 update would fail.

Could you confirm if you were able to generate the custom keys and signed image? Did you burn the fuses? If the fuses were burned, could you confirm if the default KW45B41Z-EVK Keys (SBKDK and RoTKTH)  were used (included in Chapter 5.2.1 of AN14003)? Or did you use custom generated keys for the board?

For more details on how RoTKTH and SB3KDK keys can be generated and how they are used for secure boot, please refer to AN13838 Secure Boot for KW45 and K32W

It's important to mention that the method of burning the fuse provided in these documents cannot be reversed. The keys programmed to fuses on KW45 cannot be changed anymore. Therefore, it is recommended to modify the fuse with caution.

Best regards,
Ana Sofia.

[kiranshingote]

Hi Team,

Could you confirm if you were able to generate the custom keys and signed image?

>> I am not very sure. But I created keys in PKI management, created image fron Build Image and able to write from Write Image. Not able to write anything before or later from Manufacturing tool menu.

Please find attached log file below.

Did you burn the fuses?

>> I think Yes. Please find attached log file below.

If the fuses were burned, could you confirm if the default KW45B41Z-EVK Keys (SBKDK and RoTKTH)  were used (included in Chapter 5.2.1 of AN14003)? Or did you use custom generated keys for the board?

>> I had created custom generated keys. 

### Burn RoTKTH fuses ###
blhost -t 5000 -p COM36,57600 -j -- fuse-program 0x1F {{66F09EB905D2284D3C7AC7B02D002D889D229C50FC57532EE518E9E2E2C1CE73}}

### Burn SB3_KDK fuses ###
blhost -t 5000 -p COM36,57600 -j -- fuse-program 0x20 {{E8764D3DCA61AB8ECE4BADD4FA4F14AFA71D46B31C6737CD081444A97EA9CAFB}}


I have few questions:
1. Can I not use new controller without burning fuses and or NBU firmware download to chip?
2. Whether my procedure is correct to migrate the code for package?Whether my procedure is correct to migrate the code for package?
3. Why I was not able to write .sb3 file using Manufacturing Tools menu.

[sofiaurueta]

Hello @kiranshingote ,

When the KW45 chip is received from the factory, the SBKDK and RoTKTH fuses are empty (null). Keys must first be generated and the corresponding fuses must be burned with those specific keys. Otherwise the SB3 update will fail and BLE example applications will not run successfully.

Please refer to the link below for a summarized script of the secure boot process: https://github.com/nxp-appcodehub/dm-kw45-secure-boot-scripts

Did you get any error log messages when using the Manufacturing Tool? Could you please try updating the NBU firmware using a custom SB file generated with your custom keys, following the steps described in: Processor-specific workflows — Secure Provisioning Tool 25.12

Regarding the .cproject modifications in MCUXpresso, modifying the package is not required. However, if needed, the .cproject file can be manually edited to match your specific part number.

Best regards,
Ana Sofia.